The flame photometric detector has a significant commercial importance because of its simultaneous sensitivity and specificity for the determination of phosphorous and sulfur. In particular the flame photometer is used in combination with gas chromatographs or the continuous monitoring systems (as disclosed by U. S. Pat. No. 4,805,441) for the trace analysis of these phosphorous and/or sulfur containing compounds. In some instances the detection device may be capable of determinating such compounds at concentrations as low as 10 parts per trillion. The flame detection of phosphorous and sulfur is based on the principal that, when a hydrocarbon having phosphorous or sulfur, is combusted in a hydrogen-rich flame, a chemiluminescent species is produced. These chemiluminescent species emit light at wavelengths (394-526 nm) characteristic for each element when the proper portion of the flame is viewed. The flame is fueled by H.sub.2 that is piped directly into the burner at a rate of approximately 140 ML/min. In addition nitrogen carrier gas that transfers sulfur and/or phosphorous containing compounds from the GC column, is mixed with air and flows into the burner whereby the total air flow rate is 120 ML/min. As the gases and compounds of a sample are burned in the flame, exhaust from combustion is vented through a ventilation aperture above the flame.
With this ventilation opening the detection device is exposed to ambient light that may interfere with detection of the radiation emission of the burning sample. Devices known in the prior art have attempted to solve the problem by attaching an elbow tube within the vent and an elongated bent tubing is attached thereto so the tubing extends laterally of the detection device flame, and then downward. The tubing requires ambient light to make two diffractions to enter the chamber. This apparatus however still permits light to enter the flame chamber which may cause interference. In analysis of trace amounts as low as 10 parts per trillion it is imperative that any extraneous radiation be substantially impeded to avoid interference with detection of the sample radiation emission. Moreover, the lateral extension of the pipe permits it to remain cool during operation of the instrument causing condensation on tubing as the hot exhaust is discharged from the detector. This condensation drips on laboratory tables or wherever the instrument and device is placed. In addition, the condensation may further reflect light in the tubing allowing the light to enter the flame chamber.